The present invention relates to a wire cutting apparatus for use in a winding machine which winds an electric wire or the like round a spool.
Conventionally, various winding machines for winding a wire to form a coil are normally provided with wire cutting apparatuses for cutting the end of the coil wire, for example, such as the one shown in FIGS. 1 to 3. Referring to FIG. 1, a main body bracket 1 has a pair of cutting arms 3 and 4 rotatably mounted on shafts 2 and have springs 5 connected thereto which normally urge cutting arms 3 and 4 in respective directions to separate them from each other. Each of the cutting arms 3 and 4 is respectively provided at one end with a cutting edge 7 and a clamp portion 6 and with a roller 8 at the other end, and a pin 9 at the center thereof. A rotary shaft 10, which is vertically supported on the main body bracket 1, is rotationally oscillated by a piston-cylinder device 11 through a link 12, a pin 13 and a lever 14. A lever 15 is attached to the bottom end of the rotary shaft 10 and a cam 16, which is secured to the lever 15, is provided at its ends with a wedge-shaped portion 16a and at its middle portion with a parallel sided portion 16b. A hook 17 for drawing the wire laterally of its normal path is rotatably supported on the cam 16 on the shaft 18. A tension spring 19, which is provided on the hook 17, extends between a pin 20 on the hook and a pin 21 provided on the cam 16 and a stop pin 22 is provided on the main body bracket 1 which is mounted on the stationary plate 23 through shafts 24 and 27. The shaft 24 supports the main body bracket 1. Bolts 25 secure the support shaft 24 and a shaft lock means 26 having a hole therein, through which the shaft 24 is engaged, the hole having a split groove formed in one portion. The support shaft 27 supports the shaft lock means 26 and is secured to the plate 23 in a shaft fixture 28. The shaft fixture 28 has a hole, through which the support shaft 27 is engaged, the hole having a split groove formed in its one portion. The shaft fixture 28 allows the support shaft 27 to be freely slid therethrough. The support shaft 27 is secured with a bolt 29 in the shaft fixture 28 when the position of the shaft is determined.
The cutting operation of the wire 30 and the clamping operation will be described hereinafter. The cylinder 11 is operated starting from the condition as shown in FIG. 1 to oscillate the lever 15 in one direction, and the cam 16 moves in the direction of the arrow A along rollers 8. The cutting arms 3 and 4 are pivoted about the shaft 2 as supporting points, by the forces of the spring 5, and reach the positions as shown in FIG. 2. Then, the cam 16 moves to the position X of the drawn out wire 30. A hook operating lever 32 comes into contact with a stop 31 secured to the main body bracket 1 at a position immediately before the lever 15 stops. The hook operating lever 32 oscillates, in the direction of the arrow B in FIG. 2, around a pin 33 to rotate the hook 17 in the direction of the arrow C in FIG. 2 around the shaft 18 thereby to engage the hook over the wire 30. At this time the position of the spring holding pin 20 moves, during the rotation, downwardly from a line connecting the shaft 18 with the pin 21. The hook stops at a rotation completing position due to the elastic force of the tension spring 19 and is held in this position. The operation of the piston-cylinder device 11 in the one direction stops when the parts are in this condition.
Upon the reverse operation of the cylinder 11, the hook 17 and the cam 16 retreat in the direction of the arrow D of FIG. 2. The wire 30 caught within the hook 17 is drawn into the space between the cutting edges 7 on the cutting arms 3 and 4.
When the cam 16 retreats, the wedge-shaped portion 16b of the cam 16 hits the rollers 8 to spread the rollers. The cutting arms 3 and 4 are closed against the elastic force of the springs 5. Upon the closure of the cutting arms 3 and 4, the wire 30 is cut by the cutting-edges 7, and one end 30a of the wire is clamped by the clamp portions 6. At this time, the rollers 8 are engaged by the parallel sided portion 16b of the cam 16. At the end of the retreat cam 16, the bottom end of the hook 17 comes into contact with the stop pin 22. The hook 17 rotates in the direction of arrow E around the shaft 18 as a supporting point and is restored to the first position.
The wire cutting apparatus having such a construction as described hereinabove is positioned, as shown in FIG. 3, adjacent the winding machine.
As the nozzle 35 of the flyer of the winding machine rotates in the direction of arrow F, the wire 30 is delivered from the nozzle 35 of the flyer and the wire is sequentially wound from the smallest frame 37 of the spool 36 to the largest frame 38 to provide a coil 39. When the winding operation for forming the coil 39 is completed, the wire 30 extends from the corner portion 38a of the largest frame 38 to the nozzle 35 of the flyer. With the wire in this condition, the hook 17 advances to the position X as described hereinabove to engage the wire 30 and retreats to draw the wire 30 to the position Y. The end 30a of the wire is clamped simultaneously with the cutting operation at the position Y. The coil 39, which has the cut terminal wire 30b extending therefrom, is moved between the blades 41a and 41b of the coil receiving jig 40. As the coil 39 is removed from above the spool 36, the coil receivinng jig 40 rotates 180.degree., in the case of a two-polarity motor coil. The winding operation is performed again to wind a coil around the spool 36.
However, the above-described conventional wire cutting apparatus has the following disadvantages.
(1) The conventional system of longitudinally oscillating a lever, to which a hook for drawing out the wire and a cam for opening or closing the cutting arm are secured, during the wire drawing operation and the wire cutting operation involves two movements, i.e., the forward oscillation and the backward oscillation, thus resulting in limited track reduction.
(2) Since the hook for drawing out the wire and the cam are mounted at a position where the oscillating radius of the lever is large, i.e., at the tip end thereof, the inertia is large, with the result that the oscillating time cannot be reduced.
(3) Since the hook for drawing the wire is actuated by a complicated mechanism to advance it past the position of the wire coming out of the coil and then pivoted downwardly to engage the wire, and the hook is retained in the pivoted position by the spring, deterioration of the spring makes the pivoting action of the hook unstable.
(4) When the electric wire leading from the spool to the nozzle of the flyer has been drawn into the space between the cutting edges 7 on the cutting arm by the hook and has been cut, the terminal wire leading to the wound coil can float upwardly rather than dropping due to its own weight when the wire diameter is small, and can get caught in the wire cutting apparatus, thus making it impossible to remove the coil from the spool.